Interventional radiology has been a rapidly developing area in minimally invasive (MI) procedures due to late advances in the medical imaging [1] and rapid progress in the development of procedure equipment. MI procedures have advantages such as improved patient safety and reduced discomfort, reduced hospital stay, reduced operating room cost, etc. [2-4]. The vast amount of skills that radiology residents or other specialty residents dealing with MI procedures must learn in training period makes anatomical phantoms a desired test platform on what the residents can get their first hands-on experience before everyday practice. The anatomical phantoms are not only useful for skill development in needle guidance and US probe handling for residents but also for practicing radiologist to improve their skills with new techniques and ever changing equipment and also to rise their confidence before procedures on patients. Confidence could be raised also with patient specific organ training, which is widely used in form of surgical simulators [5], but has not yet been extensively used in physical phantoms due to high cost and limited usage of the commercial phantoms.
In previous work the authors of the present invention are developed an anatomically shaped kidney phantom for interventional radiology trainees [6] with the possibility to practice variable needle thickness biopsies using US guidance. The previous version of the kidney phantom did not have drainage functionality. In order to resolve this shortcoming and to widen the spectra of the procedures of our patient specific phantoms, we decided to add drainage functionality of cysts to our kidney phantoms with the possibility also to rehearse nephrostomy drainage.
In the literature few phantoms are found that were developed for nephrostomy. Recently Rock et al [7] produced a cheap gelatine-based phantom for ultrasound-guided percutaneous nephrostomy insertion. Strohmaier and Giese [8] used porcine kidneys casted into silicone to create training phantom for all percutaneous endourological procedures (e.g. percutaneous nephrostomy, percutaneous lithotomy, endopyelotomy). The market provides few phantoms that could be used for nephrostomy training which are usually with high price and limited usage possibilities. A short list of phantoms on the market is shown in following table (probably not exhaustive):
TABLE 1Nephrostomy phantoms on the marketProducerPhantom model descriptionPriceLimbs andUltrasound Percutaneous£494.00 [9]ThingsNephrostomy TrainerMediskills LimitedPerc Trainer - Kidney model foraroundpercutaneous access training£2,500aSimbionixPERC Mentor ™ - medicalsimulator for training percutaneousaccess procedures performed underreal-time fluoroscopy
In addition from the document GB2 328 775, 3 Mar. 1999, Sami Ahmed Moussa is known a simulator for medical training comprising a replica body organs and surrounding soft tissue made of materials which have similar radiographic densities and acoustic properties to the real subjects, thus providing suitable responses to x-rays and ultrasound. However there is lack of possibilities to simulate different part of the organ, for example the human kidney contains number of calyxes, and it is very important to train the biopsy and/or drainage with all parts of the kidney involved. The opportunity to train on the kidney phantoms which have different anatomic structures gives the trainee more realistic environment and helps to avoid situations that could be harmful for the patient in real life procedures.
Document US 2003/091967, Chosack Edna, 15 May 2003 discloses a system for simulating the minimally invasive medical procedure of urological endoscopy. The system provides a simulated medical instrument and tactile and visual feedback of the simulated procedure including a mannequin with simulated ureteral opening into which the simulated endoscope inserted. Said method includes in addition the effect of dynamic contrast injection of due into the urinary tract for fluoroscopy which is used for visualisation of the endoscope in the urological organ system.
Form the document U.S. Pat. No. 5,055,51, 8 Oct. 1991, Dornier Medical Systems, Inc. is known an apparatus and method for training physicians and technicians to locate stones found in simulated human body organs, principally simulated biliary and renal calculi, and then actually fragment these calculi using ESWL. A reusable semi-anthropomorphic phantom comprises an opaque liver tissue-equivalent mass having anatomically correct simulated organ cavities associated with the midsection of a human body, principally the gall bladder and the kidney. Channels lead from the exterior of the phantom to the simulated organs. Concrements are introduced into at least one simulated organ, the channels and simulated organs are filled with a fluid-like substance, and the channels are closed with plugs. The channels are connected and there are no possibilities for biopsy of the different parts of the organ by indication that the biopsy is done to right part of the organ for example kidney. As the kidney consist more than one objects of interest after the procedures and drainage of the organs it is impossible to evaluate if the procedure was successful in a specific part of the organ.